This invention relates generally to increasing the efficiently of energy utilization of data centers. Specifically, this invention relates to a method of utilizing the waste heat generated by data centers to increase the overall energy efficiency of the facility of which the data center is a part. This is accomplished by using such waste heat to drive a heat driven engine, such as a heat driven chiller or heat pump.
A heat driven chiller or heat pump may be understood as a “three temperature machine.” Driving heat is input at high temperature, heat is rejected at a medium temperature and heat is adsorbed at a low temperature. In a chiller, the heat adsorbed at the low temperature provides the useful cooling. For purposes of this disclosure, the term “heat pump” will be used to refer to a heat driven engine that provides rejected heat as the useful product.
A data center, sometimes called a server farm, is a facility used to house computer systems and associated components, such as telecommunications and storage systems. It may be an entire building, a single room, or one or more floors or other separate portions of a building. In addition to computer systems and associated components, data centers typically house one or more redundant backup power supplies, redundant data communications connections, environmental controls (e.g., air conditioning systems, fire suppression systems) and security devices.
Adequate environmental controls are a priority for data centers because such systems must continually provide environmental conditions suitable for the computer and server equipment used to store and manipulate a business' electronic data and information systems. For example, the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., in its “2008 AHSRAE Environmental Guidelines for Datacom Equipment,” recommends an environmental temperature range of 20-25° C. (68-75° F.) and a relative humidity range of 40-55%. [These stats are correct as per latest guidelines, is there anything later than the report cited here?].
As the amount of equipment in a data center increases, and as the number computations or operations per component increase and the speed of individual components increase, the computer and other electronic components will generate increasing amounts of waste heat. Growth in the size, complexity and sophistication of data centers and the components housed therein have required correspondingly larger and more powerful air cooling and dehumidification systems to keep the data center and the equipment it houses sufficiently cool. Keeping an area and the devices within it cool can also be conceptualized as rejecting the heat generated by the equipment within the area out of the area, in this case, taking heat out of the data center.
There are over 60,000 data centers in the U.S. and Canada. Data centers consume approximately 1.7% of the U.S.'s electricity (costing about U.S. $5B per year). Large data centers can consume up to 30-40 MW in energy each year, 10 MW or more of which goes to cooling. U.S. data centers consumed 66 million MW-Hrs of electricity in 2007, and this number is growing at 12% per year (doubling every 5 years), with at least one third of this going to cooling. The present invention provides a novel method of reducing the energy demands of this cooling load and putting heat energy previously rejected as waste to use.